One eye smaller than the other

I noticed that one of my 5 1/2 week old kitten's eye is significantly smaller than the other. Also, when she blinks, she usually only blinks one of them. When she's asleep both eyes close normally. Should I be concerned or is it just asymmetry?

Have you brought her to a vet to rule out something wrong with the eye itself? Even though the eye may be smaller, she should still be able to close the lid when she blinks. This makes me think there's something not quite right with the eye.

When a cat's eyelid starts to swell due to a virus, it can give the appearance of one eye looking smaller than the other. This may progress to significant swelling and discharge, often accompanied by sneezing.

It may not be they eye but rather an irritation with the conjunctiva.

It might be a good idea to take your kitty to a vet to rule out an eye infection.